The microculture technique for growing developing sympathetic neurons and their target cells in tissue culture will be used to study the interaction between the neurons and cardiac myocytes, smooth muscle cells and other potential target cells. Special attention will be paid to whether the junctions formed are adrenergic, cholinergic or dual-function. BIBLIOGRAPHIC REFERENCES: Landis, C., P.R. MacLeish, D.D. Potter and E.J. Furshpan (1976). Synapses formed between dissociated sympathetic neurons: the influence of conditioned medium. Sixth Annual Meeting Society for Neuroscience #280. Furshpan, E.J., P.R. MacLeish, P.H. O'Lague and D.D. Potter (1976). Chemical transmission between rate sympathetic neurons and cardiac myocytes developing in microcultures: evidence for cholinergic, adrenergic and dual-function neurons. Proc. Nat. Acad. Sci. USA (in press; November issue).